According to a press release from North Carolina State University, global population crossed the 50% urban threshold on May 23rd, 2007. The UN had previously estimated that this would occur by 2010, but based on the research cited, it has in fact occurred sooner. This shift underscores a couple key factors, such as a move to a more service-oriented economy globally, a reduction in the agricultural workforce required to feed the populace (well, arguable capable of feeding people), and a likely increase in problems related to people living in close proximity, such as pluralistic ignorance.
So, if you thought something seemed different in town today, you were probably right. Somebody else just moved in out of the country, and that means at least one more car on the road...